Friday, November 19, 2010

Ages of ice samples found on the Earth cover a span approaching 200,000 years. Gas bubbles trapped in that ice can be used to learn about the composition of Earth's atmosphere at the time they were trapped in the ice. But how can we tell what the Earth's atmosphere was like before that?

Recently, USGS scientists have used a gas QMS to determine the oxygen level of ancient samples of Earth's atmosphere from a most unlikely place - amber. The fossilized resin of conifer trees, amber is interesting to scientists as a medium that traps insects, small animals, and plants, preserving them through geologic time for future study.

The recent extraction by scientists, of ancient DNA from organisms entombed in amber much like in the science-fiction novel and movie, Jurassic Park is an example of why scientists are intensely interested in amber. Minute bubbles of ancient air trapped by successive flows of tree resin during the life of the tree are preserved in the amber.

Analyses of the gases in these bubbles show that the Earth's atmosphere, 67 million years ago, contained nearly 35 percent oxygen compared to present levels of 21 percent. Results are based upon more than 300 analyses by USGS scientists of Cretaceous, Tertiary, and recent-age amber from 16 world sites.* The oldest amber in this study is about 130 million years old.

Wednesday, November 17, 2010

A new analysis of fossilized grass-pollen grains deposited on ancient European lake and sea bottoms 16-35 million years ago reveals that C4 grasses evolved earlier than previously thought. This new evidence casts doubt on the widely-held belief that the rise of this incredibly productive group of plants was driven by a large drop in atmospheric carbon dioxide concentrations during the Oligocene epoch.

The research team, led by University of Maryland Center for Environmental Science Appalachian Laboratory researcher Dr. David Nelson and University of Illinois Professor Feng Sheng Hu, examined the carbon isotope signatures of hundreds of grass-pollen grains and found that C4 grasses were already present on the landscape during the early part of the Oligocene, some 14 million years earlier than previously thought from geological evidence. Their findings are now published online in the journal Geology and will shortly appear in the print edition.

"The idea that C4 grasses originated prior to global decreases in carbon dioxide levels requires us to reevaluate the way we think about the evolution of C4 photosynthesis," said Dr. Nelson. "This new information should encourage the examination of alternate evolutionary selection pressures, such as warm temperatures or dry climates."

C4 plants compose only 3 percent of flowering plant species, yet account for about 25 percent global terrestrial productivity. About 60% of C4 species are grasses, and they dominate the world's grassland and savanna biomes, particularly those in warmer, lower latitude areas. Their ecological success results from the way these species concentrate and then fix carbon dioxide in order to power photosynthesis. While the most well known C4 plants are maize and sugar cane, both of which are critical to human consumption, there is a growing interest in their use as biofuels in order to capture carbon from the atmosphere to mitigate increasing global carbon dioxide levels.

The team used an innovative technique pioneered by Dr. Nelson earlier in his career - the Single Pollen Isotope Ratio Analysis or SPIRAL – to analyze the samples. The scientists first extracted grains of grass pollen from sedimentary rocks using a micromanipulator; then analyzed the tiny samples using a microcombustion device interfaced with an isotope ratio mass spectrometer in Ann Pearson's laboratory at Harvard University, which houses one of only a handful of these devices in the world. Through this analysis, they were able to detect the signature of C4 species from their more common C3 counterparts, because C4 and C3 plants take up different ratios of carbon isotopes during photosynthesis.

"SPIRAL enables us to detect C4 grasses at much lower abundances in geological records than previous approaches, which is helping to revolutionize our ability to study their ecology and evolution," said Dr. Hu. University of Illinois graduate student Michael Urban, lead author of the paper, continues to analyze samples from other parts of the world to look at variation in C4-grass abundance in relation to past changes in atmospheric CO2 and climate.

Physicists working at the European Organization for Nuclear Research (CERN) in Geneva, Switzerland, have succeeded in trapping antihydrogen – the antimatter equivalent of the hydrogen atom – a milestone that could soon lead to experiments on a form of matter that disappeared mysteriously shortly after the birth of the universe 14 billion years ago.

The first artificially produced low energy antihydrogen atoms – consisting of a positron, or antimatter electron, orbiting an antiproton nucleus – were created at CERN in 2002, but until now the atoms have struck normal matter and annihilated in a flash of gamma-rays within microseconds of creation.

The ALPHA (Antihydrogen Laser PHysics Apparatus) experiment, an international collaboration that includes physicists from the University of California, Berkeley, and Lawrence Berkeley National Laboratory (LBNL), has now trapped 38 antihydrogen atoms, each for more than one-tenth of a second.

While the number and lifetime are insufficient to threaten the Vatican – in the 2000 novel and 2009 movie "Angels & Demons," a hidden vat of potentially explosive antihydrogen was buried under St. Peter's Basilica in Rome – it is a starting point for learning new physics, the researchers said.

"We are getting close to the point at which we can do some classes of experiments on the properties of antihydrogen," said Joel Fajans, UC Berkeley professor of physics, LBNL faculty scientist and ALPHA team member. "Initially, these will be crude experiments to test CPT symmetry, but since no one has been able to make these types of measurements on antimatter atoms at all, it's a good start."

CPT (charge-parity-time) symmetry is the hypothesis that physical interactions look the same if you flip the charge of all particles, change their parity – that is, invert their coordinates in space – and reverse time. Any differences between antihydrogen and hydrogen, such as differences in their atomic spectrum, automatically violate CPT, overthrow today's "standard model" of particles and their interactions, and may explain why antimatter, created in equal amounts during the universe's birth, is largely absent today.

The team's results will be published online Nov. 17 in advance of its print appearance in the British journal Nature.

Climate change could trigger a 10 percent drop in China's grain harvest over the next 20 years, threatening the country's food security, a leading agriculture expert warned in comments published Friday.

Tang Huajun, deputy dean of the Chinese Academy of Agricultural Sciences, warned crop production could fall by five to 10 percent by 2030 if climate change continues unchecked, in an interview with the official China Daily.

"The output of the country's three main foods -- rice, wheat and corn -- may suffer a 37 percent decline in the latter part of this century if the government fails to take effective measures to address the impact of climate change," Tang was quoted as saying.

[...]

Tang is the chief scientist for a government project launched in September to study the impact of climate change on China's grain production over the past 20 years at 11 research stations in the north and south of the country.

"Agriculture has been the worst hit by climate change and some negative effects have become more obvious due to rising temperatures and water shortages over the past 10 years," Tang said.

Drought is the biggest threat to China's grain harvest, causing an annual average loss of 15 to 25 million tonnes from 1995 to 2005, or four to eight percent of the country's annual output, Tang said.

Noel. I am going to get to that 'How Bad Can It Get' post relatively soon. Maybe over Tday weekend. That said, I suspect 10% may be a little too conservative. Reason being that precipitation change is poorly predicted at this point, but is wildly different depending on the temperature range in models and almost always more negative for Australia, Central Asia and Africa.

A team of international researchers led by ancient DNA experts from the University of Adelaide has resolved the longstanding issue of the origins of the people who introduced farming to Europe some 8000 years ago.

A detailed genetic study of one of the first farming communities in Europe, from central Germany, reveals marked similarities with populations living in the Ancient Near East (modern-day Turkey, Iraq and other countries) rather than those from Europe.

Project leader Professor Alan Cooper, Director of the Australian Centre for Ancient DNA (ACAD) at the University of Adelaide, says: "This overturns current thinking, which accepts that the first European farming populations were constructed largely from existing populations of hunter-gatherers, who had either rapidly learned to farm or interbred with the invaders."

The results of the study have been published today in the online peer-reviewed science journal PLoS Biology.

"We have finally resolved the question of who the first farmers in Europe were – invaders with revolutionary new ideas, rather than populations of Stone Age hunter-gatherers who already existed in the area," says lead author Dr Wolfgang Haak, Senior Research Associate with ACAD at the University of Adelaide.

"We've been able to apply new, high-precision ancient DNA methods to create a detailed genetic picture of this ancient farming population, and reveal that it was radically different to the nomadic populations already present in Europe.

"We have also been able to use genetic signatures to identify a potential route from the Near East and Anatolia, where farming evolved around 11,000 years ago, via south-eastern Europe and the Carpathian Basin (today's Hungary) into Central Europe," Dr Haak says.

[...]

The ancient DNA used in this study comes from a complete graveyard of Early Neolithic farmers unearthed at the town of Derenburg in Saxony-Anhalt, central Germany.

No time. Seriously no time. Just trying to get back to doing this some.

Tuesday, November 02, 2010

A baby dinosaur approximately the size of a pug dog scurried alongside what may have been its mom or dad some 148 million years ago in what is now foothills near Denver, scientists reported today (Nov. 1) at the annual meeting of the Geological Society of America in Denver.

They caught the paleo-action in the footprints left behind there near the town of Morrison, Colo. The scientists think the dinosaur prints, a set of infant prints next to partial prints from an adult, belonged to Apatosaurus, a sauropod - giant, long-necked dinosaurs that preferred veggies - and once known as Brontosaurus.

As an adult, Apatosaurus is the largest dinosaur found in the Denver metro area, the researchers say, spanning a length of three school buses and weighing as much as eight Asian elephants.

The prints likely made by the infant Apatosaurus were tiny - if you were to place a mug over one, it would completely eclipse the print, according to one of the discoverers, Matthew Mossbrucker, director of the Morrison Natural History Museum in Boulder, Colo.

"The distance between each step is two times wider than what we observe in walking tracks, indicating the animal was at a low-speed run," Mossbrucker said. "I am not aware of any running sauropod tracks anywhere."

The trackway of running prints show only the hind paws, suggesting either that while the baby dinosaur was running, its hind paws eclipsed and removed the front paw track, or that the animal was running only on its hind paws. The tracks made by the adult in a walking mode did show a front paw print.

"We've been arguing for more than a century as to whether or not sauropods could stand up on their back paws," Mossbrucker told LiveScience. "Apparently they can, and the young can even run."

Mossbrucker notes that under the scientific definition of running, this little guy may not have met the criteria. But "if you were to see this animal scurry and scamper in front of you, you would say it's running," he said.

"In the end, we might have a baby sauropod that is running like a Basilisk lizard, a modern lizard that is mostly a quadroped, but when spooked it runs on its hindlegs," Mossbrucker said.